Synthesis: climate effects on biodiversity, abundance and distribution of marine organisms in the Benguela

Abstract

The NansClim project (2010–2013) represented a regional collaboration to assess the effects of climate on Benguela dynamics. Based on in situ (since the 1960s in Namibia and South Africa and 1985 in Angola) and satellite (since the 1980s) observations, the project focussed on four subsystems, namely the Angola subtropical, northern Benguela upwelling, southern Benguela upwelling and Agulhas Bank. This contribution summarizes the findings for selected key questions, ranging from changes in the physico‐chemical habitats, plankton, pelagic and demersal fish communities, to cross‐cutting evaluation at subsystem and regional scales. The results underline the overriding importance to of considering the combined effects of climate and fishing as drivers of the dynamics of the ecosystem components. Each subsystem currently continues to function largely as a separate entity as described in earlier reviews. However, some changes have been observed across several subsystems, e.g., a coherent shift from one relatively stable period to another occurred in the northern and southern Benguela in the mid‐1990s. Future climate change could weaken the boundaries between the four subystems. The findings underline the need for continued regional research collaboration and regional surveys focussed at ecosystem, rather than resource, assessment. Our conclusions include implications for ecosystem‐based fisheries management, and recommendations for future regional research.

Plankton productivity of the Benguela Current Large Marine Ecosystem (BCLME)

“…Likewise, off Namibia, decreases in upwelling-favourable winds and warming have been noted during all seasons (Hutchings et al, 2009b;Jarre et al, 2015). Upwelling-favourable winds off South Africa have exhibited interannual and decade-scale variations , and regime shifts have been identified from sea surface temperature, upwelling and other ecosystem indices (Blamey et al, 2012;Howard et al, 2007;Shannon et al, 2010).…”

Origin of the warm eastern tropical Atlantic SST bias in a climate model

“…The Tropical Atlantic variability (TAV) at different time scales strongly affects the African Monsoon (García-Serrano et al, 2013;Roehrig et al, 2013;Kucharski et al, 2008). Better understanding the TAV is essential for agriculture (Sultan et al, 2005) and fisheries (Jarre et al, 2015). The inter-annual TAV is partly driven by ENSO (Saravanan and Chang, 2000) and studies suggest that SST anomalies over the Tropical Atlantic can, in turn, affect the SST in the Pacific through a modulation of the Walker circulation (Rodríguez-Fonseca et al, 2009;Keenlyside et al, 2013;Terray et al, 2015).…”

Eastern Boundary Circulation and Hydrography Off Angola: Building Angolan Oceanographic Capacities

“…More recently, the NansClim project was implemented between Norway, Angola, Namibia, and South Africa (Jarre et al 2015). By using data collected through the Nansen Programme and other relevant regional data, the project aimed at studying ocean and climate variability and corresponding changes in marine biodiversity.…”